Video:http://craneaccidents.com/BigBlue/video.htm
A primary cause of the accident was wind loading (a ~26mph gust) on the
roof structure and crane boom, which caused a large moment about the
base of the structure. The base of the crane was rated for
20mph
wind
moments. Also, the soil was too soft to keep the base
directly
upright,
which caused the moment to increase further as the tipping started
(I'll
discuss in class).